Telephone system



F. TENcH TELEPHONE SYSTEM oct.) 1, 1929.

5 sheets-sheet 1 Original Filed Fetg. 27, 1926 Im Frank Tauch Oct. 1,1929. F. TENcH TELEPHONE 5 SYSTEM- original Filed' Feb. 2'7, 1926 HTF:

Oct. 1, 1929.

F. 'rENclQ-i- TELEPHONE SYSTEM original Filed Feb. 2v. 192e 5Sheets-Sheet 3 l Inuen or Frank Tauch Oct. l,hl929. F. TENCH' TELEPHONESYSTEM original Filed Feb. 27. 192s 5 Sheets-Sheet 4 NNN QM: WLAN om YI*[E] NEN .Hai

(Jet. 1, 1929. F. rrsNczH TELEPHONE SYSTEM Original F1ed...Feb 27, 1926"5 sheets-Sheet 5 *Imm-p Frank Tauch Patented Oct. 1, 1929 UNITED STATESPATENT orFIcEj FRANK TENCH, OF LONDON, ENGLAND, ASSIGNOR T0 AUTOMATICELECTRIC INC., 0F

k(IHICAGO, ILLINOIS, A CORPORATION OF DELAWARE l f TELEPHONE SYSTEMApplication led February 27, 1926,` Serial No. 91,050, and in GreatBritain June 4, 1925.` Renewed July v f 26, 1928. v

The present invention relates to telephone systems and as regards itsmain features is more particularly concerned with the operation of smallexchanges on what is known as the satellite principle, by which is meantthat the small exchanges havetheir first numericalswitches located in amain exchange and thus do not themselves require so many switchingstagesas are needed for a full sized exchange, in many cases subscribersline switches and connectors being sufficient.

Th'e'conditions of working are complicated somewhat in case the systememploys register translators, for *instance of the director type, themain principles of operation of which are disclosed in the BritishPatent No. 194,580, issued March 15, 1923. In such systems exchangeselection is usually effected by dialling the first three letters of theexchange name, thedial being provided with letters as Well as numeralsfor this purpose, and it is generally desirable for satellite exchangesto have separate names of their own in order to facilitate thechange-over when the satellite grows to-such a size as to warrant itsconversion into amain exchange. It is probably also desirable that noregister translation shall be `located at the satellite, both forreasons of first cost and also because of the addi- -ing from thesatellite will take into use a register translator located in the mainexchange. Owing to the fact that the satellite has an exchange name ofits own, it will not be decided until the subscriber has dialled thefirst three 'digits' whether or not the call is to be a local one, thatis to say, to another subscriber in the same satellite, and it is highlydesirable to arrange that ifthis is the case, as soon as the dialling oft-he first'three digits has determined the destination of the call,switching over shall take place at onceso that subsequent digitsmay bedialled direct to the local switches, one vor more digits being absorbedif necessary. To veffect this switching over operation, it has beenusual hitherto to provide number responding devices in the satelliteUwhich operate to release the trunk line tothe main exchange and theapparatus operated thereat .as soon as the critical number has beendialled. Inasmuch as a register translator is being used, however, andthus the number dialled is being recorded in any event, it is arrangedthat registration takes place on the register translator only and theswitching over operation when necessary is controlled therefrom. v

According to one feature of the invention ina system including satelliteexchanges having their first numerical switches located in ka mainexchange and having calls within the Vinitially operated by a callingsubscriber thereat is adapted to be controlled from the associated mainexchange by modifying circuit connections at the main exchange end ofthe two-conductor trunk line over which the main exchange apparatus wasfirst operated. 1

A further feature of the invention is that in a system having aplurality of satellite exchanges associated with a main exchange,registerdevices common to the various satellite exchanges and located inthe'main exchange are provided with meansfor causing circuit connectionsto bemade characteristic of said satellite exchanges 'whencalls are tobe set up to said'exchanges, so that `when a subscriber in a satelliteexchange calls a subscriber in the same exchange, a circuit is completedfor effectingl the release of the main exchange apparatus and enablingthef'con'nection to be set up independently thereof. Y

Still another feature of the invention is extending tual seizure of theidle line is adapted to be effected in response to a further operationby the calling party.

A further feature of the invention is the provision of a relay chaincomprising a plurality of relays adapted to operate on differ entmargins of current in which the energizing lead is initially connectedto the relay which operates on the smallest current and on the operationof any relay is connected to the relay having the next highest margin ofoperation. l

These features and others not specifically mentioned at this point willbe better appreciated from the following description ofone method ofcarrying the invention into effect taken in conjunction with theaccompanying drawings. This arrangement shows the invention applied to aregister translator system of the director type but clearly itsapplication is not limited to a system having these particularcharacteristics.

Referring now to the drawings, Figs. l shows a repeater R located in asatellite exchange and accessible to a calling subscriber by way of hisindividual line switch. From the repeater R access may be had by way ofthe secondary switch M to first numerical switches at the main exchangeandv over the secondary switch T to a toll operators position, which ispreferably also located in the .main exchange. Access may also be hadover the secondary switch L to local switches in the satellite itself,the repeater R- in this case being cut out and battery feed taking placefrom the connector according to usual practice. Figures 2, 3, ll, and 5,show a register translator or director located in the main exchange andmodified in accordance with the invention so as to control switchingoperations at the repeater R in the satellite. In the arrangement shown,when the trunk line to Fig. 2 is taken into use, the switch S is startedhunting for a free first code selector such as DS, which is arranged torespond to the first digit dialled and thereupon hunt to find a freeregister translator. This then responds to the remaining two digits inthe exchange name and also to the numerical digits, four of which willbe assumed to be employed infthis system. The

digits representing the exchange name are converted by the registertranslator into an exchange code which may comprise from one lto sixtrains of impulses, by means of which the connection is routed to thedesired exchange and the numerical impulses are subsequently sent outunchanged by the register translator.

The general method of operation of the arrangement ac'cording to theinvention will first be described briey. Suppose in the first yinstancethat the subscriber in the satellite Vwishes to set up a call to asubscriber whose line is connected to any exchange in the system exceptthe originating satellite. It may be pointed out in passing that when acall is extended to a subscriber in a satellite connected tc the sam-emain exchange as the originatingsatellite, theconditions are in no waydifferent from those which obtain when a call is extended to an outsideex- 'llilhen the trunk line is seized, the switch SS commences tooperate and seizes a free first code switch such as DS. The subscribermay now dial the digits corresponding to the number of the wanted linewhereupon the first digit'operates the switch DS, which then seizes anidle register translator connected to the particular level to which ithas been raised. The remaining digits are stored in the registertranslator which in due course sends out the required series of impulsesfor completing the wanted connection. When all the digits have beendialled, however, a momentary signal is sent back to the repeater Ft toplace the apparatus there in a condition to receive'supervisory signalsas distinct from a setting condition in which it is adapted to receivesignals for producing particular switching operations associated withthe setting up of the connection.

Consider now the case in which the calling party wishes to obtain accessto the toll operator, in which case he will dial the digits TCL; theinitial operations., however, are rthe sainel as before up to the takinginto use of a register translator and the receipt by it of vthe last twodigits of the exchange name.

ysuitable nature isgiven to the toll operator,

who then attends to the calling partys requirements.

A further case remains to be considered, namely, that in which the'calling party wishes to set up a connection to a subscriber attached tohis own exchange, which may, therefore, beconipleted entirely locally.Tf, however, the satellite has a separate exchange name, as is assumedto be the case, it wll not be determined until he has dialled the firstthree digits corresponding toy theexchange name that the call isdestined for the satellite to which he is connected. Consequently asbefore a register translator is taken into use and responds to theexchange digits but in this vcase after the first three digits have beenreceived, a different signal is sent back to the repeater R and thiscauses the switch L to be connected up, while switches M and T and ltheremainder of the apparatus operated in the repeater R are released. Inevery `case the register translator is released as soon as ithasperformed the functions required of it.

The operation of setting up various types of connections having beenconsidered briefly, these connections willnow be traced through indetail. In the first case it will be assumed for the sake of conveniencethat the wanted partys line terminates in a satellite connected t-o thesame main exchange as the originating satellite, but it will beunderstood that the operations are substantially the same if theconnection is extended to any other exchange in the system other thanthe local exchange. Vhen the contacts 1, 2, 3, and 4 are seized byacalling party over his line switch, a circuit is completed overarmatures 16 and 19 and their back contacts for line relay 5, whichthereupon operates and at armature 7 completes a circuit for releaserelay 9. This thereupon at armature 13 prepares a circuit for relay 33and at armature 11 connects earth to the release trunk conductor so asto maintain the line switch operated and also to complete a circuit forthe left-hand winding of polarized relay 37. At armature 11 a furthercircuit is completed which extends over armature 17 and its backcontact, armature 30 and its back contact, winding of relay 21,interrupter contact and magnet 26 to battery; while at armature 12, testwiper 57 is connected to the junction of relay 21 and magnet 26 so thatthe switch M commences to hunt in known manner. A branch of the abovetraced circuit for relay 21 extends over back Contact and armature 24and through relay 39 to battery sothat relay 39 thereupon operates. Atarmatures 40 and 42 it prepares circuits for relays 43 and 46 and cutsout the right-hand winding of relay 37, and at armatures 40 and 41completes circuits previously prepared at armatures 10 and 14 forstarting the hunting operation of the switches L and T. It will be notedthat at this time no circuit is completed for relays 15 and 27 so that.it is impossible for these relays to operate when their associatedswitches come to rest on contacts connected to idle lines. When theswitch M finds a free trunk line, for instance that comprisingconductors 59 and 60, there will be no earth on the contact 61 engagedby wiper 57; consequently relay 21 is not longer short-circuited andoperates, thereby at armatures 22 and 25 connecting-up wipers 56 and 58,at

armaturey 23 opening the initial hunting circuit and fecding'earthforward to wiper 57, and at armature 24 opening the initial energizing`circuit of relay 39. By the operation 'of armatures 22 and 25, however,circuits are completed over conductors 59 and 60 for the relays 43 and46 and accordingly these now operate, thereby at armatures 44 and 47comcuit, as well as relay 43, and at armature 93 completes a circuit forswitching relay 94 and magnet 103 in series, and at armature 92 connectstest wiper 107 to the junction of relay 94 and magnet 103. The switch SSthereupon commences to hunt in known manner and when test wiper 107engages a contact which is not earthed, relay 94 operates, thereby atarmatures 95, 96, 97, 99, 101 and 102 connecting up its wipers, atarmature 97 also opening the' circuitffor relay 91; moreover at armature98 it opens the original hunting circuit and prepares -a locking circuitfor itself. The operation of armatures 97 and 101 complet-es a circuitover'the normally closed springs controlled by armatures 112 and 114 forline relay 115. This, therefore, operates and at armature-116 completesa circuit for relay 118. This relay upon operating in its turn atarmature 119 connects up earth to replace that previously providedbyarmature 93 and at armature 120 opens a point in the release magnetcircuit and prepares the impulsing circuit. All the above describedoperations take place before the subscriber operates his dial and itmaybe arranged if necessary, that jwhen they havewbeen completed hereceives dial tone soas to indicate that it is then in order for him tostart impulses.

\ Suppose that. the number of the wanted party is UNDerwood 3456, inwhich case the first digit dialled corresponding to the letter U wouldbe 8. Vhen the loop is opened, relay 5 deenergizes and at armature 7completes a circuit for relay 33, which being slow to release, remainsoperated throughout the train of impulses. Relay 33 at armatures 34 and36 cuts out relays 43 and 46 and places a direct loop across thespeaking conductors so as to improve the impulsing conditions, and atarmature 35 completes a substitutey locking circuit for relay 39. Theimpulses are now repeated over the outgoing trunk conductors 59 and 60by armature 8 so that relay 115'of the switch DS 'deenergizescorrespondingly. The contacts 6 on relay 5 are provided to ensure aproper first impulse before relay 33 had had time to operate, and aswill be seen, they are cut out when this operation has occurred. Eachtime the relay 115 in the switch DS deenergizes, an impulse istransmitted to the vertical magnet 133, which accordingly raises thewipers, 140-145 to the eighth level. Relay 123 is energized in parallelwith magnet 133 throughout the train of impulses and at armature 124prepares a circuit for stepping relay 125 which becomes operative assoon as off normal contacts 12S close. Relay 123 also operates armature130, but this is without effect at this stage of the connection. Relay125 upon operating, at armature 126 completes a locking circuit foritself, and at armature 127 prepares a circuit for the rotary magnet129. When relay 123 deenergizes at the end of the train of impulses, atarmature 124 a circuit is completed for the rotary magnet which advancesthe wipers one step and at its interrupter contact 131 opens the lockingcircuit for relay 125. The hunting operation of the switch DS then takesplace in known manner by the inter-action of relay 125 and magnet 129until a free register translator is encountered. Relay 132 is then nolonger short circuited and operates, thereupon at armature136-connecting earth to wiper 142 and at armature 137 opening a point inthe circuit of vertical magnet 133 and preparing a circuit for repeatingimpulses to the register translator. At armature 134, 135, and 139 anumber of control circuits are prepared which will be describedsubsequently. When earth is fed forward to lead 148 over wiper 142,release relay 171 is operated and at armature 172 opens the restoringcircuit for the switch OCS and prepares a locking circuit over lead 174,and at armature 173 opens the circuit for the release magnet of thevarious switches in the register translator.

When the subscriber dials the next digit, which in the case consideredis 6, six impulses are repeat-ed by relay 5 as before, so that relay1.15 is momentarily deenergized six times. Upon each deenergization thefollowing circuit is completed: earth, back con- Jtact and armature 117,armature 120 and its front contact, armature 137 and its front contact,wiper 143, leads 149, Winding of relay 152. wiper 166 of the inputcontrol switch ICS, lead 189, vertical magnet 201 to battery. By theoperation of vertical magnet 201, therefore, the code switch CS, whichis a vertical and rotary switch of known tvpe arranged to respond to thesecond and third exchange digits, is raised to the sixth level. Relay152 is energized in series with the vertical magnet and being slow,remains energized throughout the train of impulses. At armature 153 itcompletes a circuit for slow relay 157 and at armature 154 completes acircuit which will be described shortly. At the end of the train ofimpulses when relay 152 releases, a circuit is momentarily completedfrom earth, armature 153 and its back contact, armature 159 and itsfront Contact for magnet 162. The wipers 163-166 of the switch ICSarethus advanced one step in readiness to route the next series of impulsesto rotary magnet 202. During the first train of impulses sent to theregister translator, relay 123 is again operated and at armature 130 acircuit is now completed as follows: earth, resistance 100, armature 99and its front contact, wiper 108, front contact and `armature 130,armature 138 and its front contact. wiper 144, lead 150, armature 154and its front contact, lead 155 armatures 272, 268, 264, and 261, andtheir respective back contacts, normally closed springs controlled byarmature 262, winding of relay 256 to battery.

A short explanation may be given at this point of the arrangement of therelays' 256, 253 and 259. @ne of these relays is pro vided for eachsatellite associated with the main exchange to which connections can beup under the control of the register translator shown. Hence it will beappreciated that in order to indicate the l'iexibility of thearrangement according to the invention, the ext-reine case had beenchosen in which no less than four satellites connected to one mainexchange have their exchange names beginning with the same letter orletters which appear in the same finger hole of the dial. The relays256-259 are each individual to a particular satellite in that thecontacts controlled by each relay are connected to the contacts of theswitch CS on which the wipers are set when the particular exchange nameis dialled. lt will be assumed that relay 259 is associated with theexchange Un derwood to which a connection is now being extended, whilerelay 258 is associated with the exchange Vanguard from which the callis being initiated. These relays are, however, arranged to operate ondifferent margins of current, and in the arrangement shown, the relay256 is the most sensitive and the others are less sensitive in order.Operating in conjunction with these relays are resistance such as 100(shown in Fig. 2), which are associated with the trunlr lines leadingfrom any particular satellite; thus for one satellite the resistance 100will be entirely absent, that is to say, there will be a direct earthconnected to the front contact of armature 99.

In case a call is from the Underwood exchange, earth is extendeddirectly to lead 155 during the second train of impulses represent` ingthe exchange name and effects the operation of all the relays 256-259 inturn. For the second satellite, i. e., the exchange Vanguard, nowcalling, the resistance 100 is comparatively low but is sufficient toprevent the operation of relay 259, while permitting that of -relays256-258. Similarly for the other two satellites progressively higherresistances are employed so that or the fourth satellite only relay 256is able to operate and not any of the others. y

The connection corresponding to resistance is left open at the secondaryswitches used to extend local lines to the directors.

As mentioned above, since the present call is being set up fromVanguard, the resistance 100 is comparatively low so as finally topermit theopera-tion of relay 258, but no-t relay 259. Hence when thecircuit above traced is completed, relay 256 operates; at its armature262 completes a locking circuit for itself to lead 174 and at itsarmature 261 transfers its original energizing circuit to relay 257.This relay, therefore, also operates, locks up at armature 266, atarmature 265 opens the locking circuit of relay 256 so that this isdeenergized, and at armature 264 transfers the eny ergizing circuit torelay 258. This then operates with similar effect, and the energizingcircuit is then transferred to relay 259. As explained above, however,owing to the resistance 100, relay 259 cannot receive sufficient currentto cause it to operateI and consequently the final result is that-relay258 remains operated, being locked up to lead 174 over armature 273 andits back contact. Relay 258 at its armature 253 and 267 preparescircuits which will not come into use in this case since the call is tobe extended through the main exchange, but the operation of which willbe described subsequently. y

When the subscriber dials the letter D corresponding to the third digitin the wanted exchange name, three interruptions are produced in thecircuit of relay 5 and these are repeated` as previously described, torelay 115. Relay 115 pulses as before and conse* quently three impulsesof current are transmitted over lead 149 through the winding of relay152, over wiper 166 now in second position and over lead 190 to therotary magnet 202 of the switch CS. This switch accordingly advancesitswipers 203-206 three steps so that they come to rest in engagementwith contacts 207-210. Relay 152 is' energized throughout the series ofimpulses and on their termination deenergizes as before and completes acircuit for magnet 162 so that the wipers of the switch ICS are movedinto third position. Consequently when the first numerical digit isdialled, a ltrain of three impulses is routed over lead 191 to thestepping magnet 301 of the first digit register M1. Similarly theremainingnumerical digits 4. 5, and 6 are registered on thesecond, thirdand fourth dig- 'it registers M2, M3, and M4'. It will be assumed thatthe digits 863 representing the exchange name Underwood are translatedby It will be seen, therefore, that as soon as the switch ICSmoves intothird position anl distributing frame IDF, terminal 3 on thel left-handside, and thence over conductor 223 corresponding to a train of threeimpulses to the fifth contact in the bank of wiper/187 of the switchSCS. Moreover the following` circuit is now completed: earth, wiper 164inl third position, interrupter I, back Contact and armature 182,winding of magnet 183 to bat-l` tery. Magnet 183, therefore, operates:and

upon releasing, when the interrupter contacts subsequently open,advances the wipers'1`86 and 187 of the sender control switch SCSAintoengagement with their respective second bank contacts. A circuit isthereupon completed i L from earth on the bank of wiper 186 for thepick-up relay'v 175, which at armature 17 6l removes one of the shuntsround the impulsingfloop extending over leads 146 and v147, at armature177 completes a circuit for the magnet 167 of the output control switchOCS and at armatureV 178 connects a multiple earth to lead 148, whichis, however, without effect at the presenttime. When the interruptercontacts again open, springs 185 are opened and an interruption isaccordingly produced in the outgoing loop over conductors 146 and- 147.When the interrupter cont-acts close, the impulse is terminatedand thewipers 186 and 187 arevadvanced. one step. This operal y tion continuesuntil three interruptions have been produced in the loop whereupon atthe end of the third impulse wiper 187 is adi vanced into engagementwith the cart-hed fifth contact in its bank. A circuit is then completedfor the stop relay 179, which thereupon operates; at its armature 180shunts the sending contact 185 so that further operations of magnet 183are ineffective for sending impulses, at armature 181 completes alocking circuit for itself and opens the circuit of magnet 167, wherebythe wipers 169 and 170 are advanced one step in readiness to control thesending of the next digit, and at armature 182 disconnects theinterrupter I and completes a local circuit for magnet 183 which extendsover the interrupter contacts 184 and wiper 186. The switch SCS,therefore, rotatesautomatically until wiper 186 fails to find earth, f

the register translator into the digits 379. and thus the next digit, inthis case'7, is sent out under the control of the switch SCS in arepeater R of the removal o battery and manner similar to that justdescribed. In view of the fact that the operation of a sending switchsuch as- SCS is well known in the art, no further detailed descriptionof the sending operation will be given. It will suffice to say that atthe end of each train of impulses wheny wiper 187 finds earth, theswitch OCS is advanced one step and thereupon alters the circuits sothat the wipers 203-206 in turn control the sending of the exchangeselecting digits, and subsequently the wipers of the digit registersM1M4 control the sending of the numerical digits. It will be seen thatthe jumpering to terminal 224 from which the so-called skip conductor156 extends is for the purpose of moving the switch OCS through the 4thexchange digit position since in the present case only three series ofimpulses are required to route the call tok the desired exchange. Thesending operation, it will be understood, commences as soon as the fullexchange name has been dialled and will continue automatically so longas the digit registers have been operated in advance. In case, however,the subscribed should be somewhat slow to dial so that the sending outyof impulses catches up with the registering, sending will be delayed bythe special circuit completed for relay 179 over lead 188 and the wiperof any digit register in its normal position.

Considering now, however, the further operation of the switch ICS, aspreviously pointed out, at the end of each train of incoming impulsesthis switch is advanced one step and'since it is assumed that the systemis a sevendigit one, one digit being received by the switch DS and sixby the register translator, it will be appreciated that when thecomplete number has been dialled, the wipers of thek switch ICS will beadvanced to seventh position. Thus after the end of the last train ofimpulses when rela 152 releases, the usual circuit is complete over backcontact and armature 153 for the magnet 162 andthe wipers 163-166 areadvanced one step. While relay 157 still holds up, however, earth isconnected by way of wiper 163 and the seventh contact in its bank,overarmature 158 to lead 151, thence over wiper 145, front contact andarmature 139, and winding of relay 113 to battery, and also over wiper165 and the seventh contact in its bank, front contact and armature 160,back contact and armature 154, lead 150, wiper 144, front contact andarmature 138, armature 130 and its back contact and winding of relay 111to battery. Relays 111 and 113 .both operate at this time and at their-armatures 112 and 114 disconnect battery and earth from the lineconductors 59 and 60, at the same time completing a holding circuit forthe line relay 115 so that this shall not deenergize. The eli'ect at theearth from conductors 59 and 60 is to deenergize both relays 43 and 46,whereupon the holding circuit for relay 39 is opened at armatures 44 and47 and it deenergizes. Thereupon at armatures 40 and 42 it cuts outrelays 43 and 46 and connects up the right-hand winding of polarizedrelay 37 for supervisory purposes, and at armaturesl 40 and 41 opens thecircuits to the magnets 20 and 32 so as to prevent any useless steppingoperation of these magnets during the remainder of the connection. Whenrelay 157 deenergizes an instant later, the circuits for relays 111 and113 are opened. These relays, however, are arranged to beslow-torelease, and accordingly they hold up for a short intervalsufficient to endure the deenergization ofrelay 39 in the repeater R,which relay is Vonly slow enough to ensure that it shall not denergizewhen relay 21 pulls up. l/Vhen relays 111V and 113 linally fall away,the conditions in the switch DS are restored to normal and current flowsthrough the winding of the relay 37, but not in such a direction as tocause it to opcrate.

To return now to the operation of the register translator, when thewiper 170 reaches its last position after all the digits have been sent,earth is connected to lead 149 and is extended over wiper 143, frontcontact and armature 137, front contact and armature 120, armature 117and its front contact, wiper 110, front contact and armature 102,normally closed springs controlled by armature 82, winding of relay tobattery. Relay 80 thereupon operates, at armature 82 locks itself up tothe release trunk conductor and at armatures 81 and 83 connects thespeaking leads through, at the same time disconnecting line relay 115.This relay, therefore, deenergizes and at armature 116 opens the circuitof relay 118. Re-

lay 118 upon denergizing in its turn, at armature 119 removes thelocking earth for relays 94 and 132 and also removes earth from lead148, whereupon relay 171 in the register translator is released.Thereupon at armature 173 earth is connected to lead 193 so as tocomplete circuits for the release magnets of the switches ICS and Ml-M4which are accordingly restored to normal.' Accordingly, the switches SSand DS and the register translator are released and the latter may betakeninto use for setting up other connections. In the repeater,polarized relay 37 is operated by reversal of current over the speakingleads when the called party replies, and at its armature 38 connectsearth to contact 4, thus completing a circuit for the calling partysmeter. At the end ot the conversation, when the calling party hangs up,the circuit for relay 5 is opened and it deenergizes, thereby openingthe circuit of relill) lease relay 9 lat armature 7, and at armature 8opening the circuit over the out-going leads so that all the switchesahead are released in known manner. All the apparatus involved in theconnection has, therefore, now been restored to normal and is availablefor use in completing other connections.

` Consider now the case in which a subscriber in the satellite exchangeVanguard wishes to set up a toll call; he accordingly, dials the lettersTOL, the numerical equivalent of which is 805. Assume furthermore thatthis line switch seizes the repeater R, that the switch M again selectsthe outgoing trunk comprising conductors 59 and 60, and that switch SSagain takes into use the first code switch DS. In response to thedialling of the first digit T, the switch DS is raised to the eighthlevel as before and hunts to find a free register translator. Assumingfor convenience that that shown in the drawings is again employed, inresponse to the .second digit O the wipers of the switch CS are raisedto the tenth level and in response to the third digit 5 they are rotatedinto engagement with t-he fifth set of contacts in this level, which areassumed to be the contacts 212-215. During the dialling of the digit O,the discriminating earth is connected up to relays 256- 259 as beforeand consequently again relay 258 remains energized. The switch ICS isadvanced between the successive series of impulses as previouslydescribed, and as soon as its wipers move into third position, thefollowing` circuit is completed: earth, wiper 164 and the third contactin its bank, wiper 170 and the iirst contact in its bank, lead 192,wiper 203, contact 212, armature 254 and its back contact, armature 253and its front con-- tact, lead 151, wiper 145, front contact andarmature 139, winding of relay 113 to bat tery. Relay 113 uponenergizing in this circuit, at armature 114 opens the circuit of relay43 in the repeater R, leaving relays 46 and 115 held up at this time inseries. `Upon the decnergization of relay 43, the following circuit iscompleted: earth, armature 35 and its back contact, armature 45 and itsback contact, vfront contact and armature 49, winding of relay 27,interrupter Contact and rotary magnet 32 to battery. Since the switch Thas preselected an idle trunk ex` tending to the toll operatorsposition, there is no earth at this time connected to wiper 54. Hencerelay 27 now operates; at armatures 28 and 31 connects the ,speakingleads through to wipers 53 and 55, at armature 29 opens the huntingcircuit and connects earth forward to wiper 54 to busy the line to otherswitches, at armature 29 opens the hunting circuit for the switch M, andat armature 30 completes a locking circuit for itself, at the same timeopening the circuit of relay 21. Relay 21 accordingly vdeenergizes andat armatures 22 and 25 opens the outgoing loop over conductors 59 and 60so that relay 115 is deenergized. Consequently after a short interval,relay 118 deenergizes also and ai armature 119 removes earth fromholding conductor 148 so that the register translator is released int-he manner previously described. At the repeater R the connection ofrelay 43 and 46 to the outgoing trunk conductors leading to the tolloperator-s position causes a visual signal to be given to indicate tothe operator that a .subscriber is awaiting attention. She may thencomplete the call in known manner and with the circuits shown all theoperated apparatus would be released when the calling party hung up hisreceiver. i

It is usually desirable, however, that the operator shall have controlofthe release of the connection and this could be brought about in thepresent instance by arranging for the operator to connect earth to theupper trunk yconductor thereby bringing down relay 43, and over anadditional back contact on this relay and a front contact on relay 46,an auxiliary circuit could be completed for relay 9 so that theconnection would re-7 main set until its release was initiated by theoperator. Alternatively, the operation of relay 27 could be arrangedtoopen the circuit of relay 39 so that relays 43 and 46 are lcut out,and the polarized relay 37 connected across the line. Such arrangements,however, are not shown in full as theyv do not strictly form part of thepresent invention and suitable circuits could readily be advised bythose skilled in the art. It will be noted that when the digits TOL aredialled from the main exchange, the toll operators position is reachedby the transmission of the digits 5 and 2, switching-over then takingplace immediately.

The case remains to be considered in which the subscriber wishes to setup a local connection, that is to say, a connection to a sub` scriber inthe Vanguard satellite exchange. For convenience of description it willbe assumed that, as before, whenhe removes his receiver, he takes intouse successively the repeater R, the trunk line comprising conductors 59and 60 and its associated switch SS, and the first code switch DS.v Thenumerical equivalent of the exchange name Van` guard is 826 andconsequently when the first digit is dialled the switch DSwill be raisedto the eighth-level as before and will thereupon hunt to find va freeregister translator, for instance, that shown. The remaining digits 26of the exchange name will thenbe set up on the code switch CS in themanner previously described, the wipers 203-206 bef the second digit the4earth through resistance 100 will be Connected to the discriminatingrelays 256259 and as in the previous cases, relay 258 corresponding tothe Vanguard exchange will be locked up.

When the complete exchange name has been dialled, the switch ICS movesinto its third position and a circuit is then completed as follows:earth, wiper 164 and the third contact in its bank, wiper 170 and thefirst contact in its bank, lead 192, wiper 203, contact 218, lead 222,armature 267 and its front contact, lead 150, wiper 144, front contactand armature 138, armature 130 and its back contact, winding of relay111 to battery. Relay 111 thereupon at its armature 112 opens thecircuit for relay 46, while leaving relays 115 and 43 maintainedenergized in series. With these conditions at the repeater R, namely,relay 43 energized and relay 46 deenergized, a circuit is completed fromearth, armature 35 and its back contact, armature 45 and its frontcontact, back contactl and armature 48, windingof relay 15, interruptercontact and magnet 2O to batte-ry. Relay 15 upon operating, at armatures16 and 19 connects the speaking leads through the Wipers and 52 whichare in engagement with a trunk extending to the preselected free localswitch, at armature 18 completes a locking circuit for itself, opens thehunting circuit and feeds earth forward to wiper 51, and at armature 17opens the circuit of relay 21. When relay 21 deenergizes, the outgoingloop over conductors 59 and 60 is opened at armatures 22 and 25, andaccordingly the partially operated register translator is released asdescribed above. The operation of armatures 16 and 19 also opens thecircuit for line relay 5, which thereupon at armatures 6 and 8 opens thecircuits of relays 43 and 46 and at armature 7 opens the circuit ofrelay 9 which, therefore, deenergizes after a short interval. Theinitial earth is thereupon removed from o the release trunk conductor atarmature 11,

but before this takes place earth will have been fed back from theseized local switch over wiper 51 so that relay 15 and the switchingrelay of the subscribers line switch are maintained operated. Relay 39will deenergize shortly after its locking circuit is opened at armatures44 and 47 so that all the apparatus originally operated in the repeateris restored to normal.

The above described switch-over operation takes place immediately afterthe termination of the third series of impulses, when it is definitelyknown that the call is to be completed locally; consequently when thesubscriber dials again for the numerical digits, the interruptionsproduced by his calling device directly operate the line relay of theseized local switch, which is set in known manner, and one or moresucceeding switches are then taken into use to complete the desiredconnection. In order that the number scheme may be kept uniform and toallow for growth, it

is probably desirable to employ four-ligure numbers for designatingsubscribers connected to the various satellite exchanges, even thoughthe size of an exchange does not exceed a thousand lines so that threedigits would be sufficient. If three digits only or less were required,the extra impulses could be absorbed by the use of a digit-absorbingswitch in the local switch train, which is proba-bly the preferablesolution, or alternatively by modifying the register translator slightlyso that it did not switch until one or more numerical digits had beenreceived so that the extra digits would be absorbed by the registertranslator. For instance the connection between the third and fourthcontacts in the bank of wiper 164 could be opened on the operation ofrelay 258, though this might be objectionable as it would slow up theoperation in the case of calls which did not require switching over. Itwill be seen from Fig. 4 that the code for obtaining access to theVanguard exchange from any other exchange is 358, contact 221 beingjumpered to terminal 224 to cause the switch OCS to move through itsfourth position.

According to the invention, therefore, a very simple arrangement hasbeen devised which does away with the necessity for number recordingdevices at satellite exchanges thus reducing the cost of the apparatusand simplifying the work of maintenance. lt will be understood, ofcourse, that the arrangement shown is only one example of carrying theinvention into effect and that various modifications could be made ifthought necessary or desirable. For instance, it might be found that itwas not satisfactory for the switches L and T to select idle lines, butnot seize them and in this case arrangements could be made whereby thelines were seized and if not required were released when relay 39deenergized on the completion of dialling. Moreover since the subscriberonly dials the let-ters TOL to reach the toll operator, the switch Tneed not hunt at all until it is taken into use as no special signalshave to be transmitted to the toll operators position.

It will be appreciated moreover that the number of relays in themarginal chain could be altered as desired, the limit being set by thenecessity for a sufficient operating margin between the successiverelays of the chain. Clearly also the arrangement of this marginal chainis not limited in its application to the particular circumstances shown.

What is claimed is:

1. A telephone system including satellite exchanges having their firstnumerical switches located in a main exchange and having calls withinthe satellite adapted to be completed entirely locally in which thenumber recording devices for determining whether a call shall beswitched locally are located at the main exchange.

2. A telephone system including satellite exchanges and employingregister controllers, in which numbers dialled by a subscriber attachedto a satellite exchange are received by a register controller in themain exchange, and means in said register controller for sending baci: aspecial signal to the satellite in case the call is to be completedlocally.

3. A telephone system employing register controllers seized by Way ofrepeaters inA which when the full number of digits have been dialled adistinctive signal is transmitted from the register controller tooperate appaiatus in the repeater, and means in said register controllerfor transmitting said signal as set forth.

l. In a telephone system, a satellite ex-v change and a main exchange,means compris-l ing automatic switches in said satellite exchange onlyfor completing a local connection, and a register sender in said mainexchange for determining Whether or not a call shall be completedlocally.

5. In a telephone system, a satellite exchange and a main exchange, aregister sender in said main exchange. means for transmitting the digitsdialled by a calling subscriber Whose line terminates in said satelliteexchange to said sender, means in said sender responsive to the receiptof saidv means operative responsive to the seizure ofsaid'repeater forseizing one of said register senders, and means in said senderresponsive to the registration of a complete telephone number fortransmitting a distinctive signal f from said sender to operate saidrelays.

7. In a telephone system, a first exchange, land a second exchange, atrunk line connecting the first exchange' With the second exchange,register senders in said second exchange, means responsive to a calloriginating in said rst exchange' for seizing one of said registersenders over said trunk line` and means in said register senderresponsive to the registration of a complete telephone number fortransmitting a signal back over said trunk line to the first exchange.

8. In a telephone system, a main exchange, a satellite exchange, atwo-conductor trunk line connecting the' satellite exchange with themain exchange, apparatus in said satellite exchange initially operatedby a calling subscriber thereat for connecting his line With said trunkline, apparatus in said main exchange operated over said trunk line tomodify the circuit connections at the main exchange end of said trunkline, means controlled by the modified circuit connections fordisconnecting the calling line from said trunk line, and automaticswitches in said satellite exchange then operated under control of thecalling subscriber for completing the connection to the called line. i

9. In a telephone system, a main exchange, a plurality of satelliteexchanges associated With said main exchange ley-trunk lines, a registersender in said main exchange, said register sender common to saidsatellite exchanges and having means for causing circuit connections 'tobe automatically made characteristic of the calling satellite exchangeswhen calls are to be set up in said satellite exchanges, means in saidregister sender responsive to a calling subscriber in one of saidsatellite exchanges dialling the office code corresponding to thesatellite exchange in Which the calling line terminates for effectingthe release of' said register sender, and automatic' switches `in Ysaidsatellite exchange directively operated responsive to the callingsubscriberl dialling the remaining digits of the desired called linetelephone number for completing the desired connection independent ofsaid register sender.

f l0. In a telephone system, a main exchange, a plurality of satelliteexchanges connected to said main exchange by trunk lines, registercontrollers in said main exchange, means for seizing one of saidregister controllers from one of said satellite exchanges, a circuit,means responsive to the y seizure of said register controller forpreparing said circuit to send back a special signal to said satelliteexchange, means for setting said registercontroller in any one of aplurality of positions corresponding to said exchanges, and means forcompleting said circuit onlyin case said register controller has beenset in a position corresponding to the calling satellite exchange.

` 11.v In a telephone system, a main exchange, a'plurality of satelliteexchanges connected to said main exchange by trunk lines, registercontrollers in said main'exchange, means for seizing one of saidregister controllers from one oit' said satellite exchanges, a circuit,means responsive to the seizure of said register controller forpreparing said circuit to send back a special signal to said satelliteexchange, means for setting said register controller in any one of aplurality of positions corresponding to said exchanges, means forcompleting said circuit only in case said register controller has beenset in a position corresponding to the calling satellite exchange, andmeans responsive to the completion of said circuit for releasingsaidregister controller.

change, a plurality of satellite exchanges connected to said mainexchange by trunk l lines, register controllers in said main exchange,means for seizing one of said register controllers from one of saidsatellite exchanges, a circuit, means responsive to the seizure of saidregister controller for preparing said circuit to send back a specialsignal to said satellite exchange, means for setting said registercontroller in any one of a plurality of positions corresponding to saidexchanges, means for completing said circuit only in case said registercontroller has been set in a position corresponding to the callingsatellite exchange, means responsive to the completion of said circuitfor releasing said register controller, and automatic switchesdirectively controlled by the calling subscriber independent of saidregister controller fior completing a local connection.

18. In a telephone system, a main exchange, a satellite exchange, a tollexchange, a first trunk line connecting said main exchange with saidsatellite exchange, a second trunk line connecting said satelliteexchange with said toll exchange, a register 4device in said mainexchange, means responsive to a call by a subscriber in said satelliteexchange for seizing said register device over said first trunk line,means for setting said register device in a position corresponding tosaid satellite exchange or said toll exchange, means responsive toeither of said last setting means for releasing said register device,means operative in case said reg istering device was set in the positioncorrespending to said toll exchange for connecting the callingsubscriber to said second trunk line extending to the toll exchange, andmeans in said satellite exchange operative responsive to the callingsubscriber dialling the remaining digits of the desired called linestelephone number in case said registering device Was set in the.position correspending to said satellite exchange for completing theconnection to the called line.

14. In a telephone system, a main exchange, a pluralityy of satelliteexchanges associated with said main exchange by trunk lines, anoperators position, local automatic switches in each of said exchanges,a register sender y in said main exchange, means for completing localconnections from a calling to a `called subscriber in the same satelliteexchange, for completing connections from a calling subscriber in onesatellite exchange to a called subscriber in another satellite exchange,and for completing connections from a calling subscriber in one of thesatellite exchanges to said operators position, said means includingonly the switches in the satellite exchange in which the localconnection is completed. the switches in the main exchange in theconnection from one satellite exchange to another, and a switch in thesatellite exchange originating the call to the operators position, andmeans controlled by said register sender responsive to the digitsdialled by the calling subscriber to complete any one of saidconnections :tor routing the call to matically operated during theoperation ot f said register controller.

16. In a telephone svstem, a trunk line comprising only two conductors,an impulse repeater, a register controller accessible to said repeaterover said trunk line, and means in said repeater responsive to a signaltransmitted 'from said register controller for conditioning saidrepeater to respond to supervisory signals.

l?. In a telephone system, a calling line, a non-numerical switch, meansresponsive to the removal oi the calling subscribers receiver forseizing said switch, a plurality ot trunkr lines, means responsive tothe seizure ot said switch for causing said `switch to preselect an idleone of said trunk lines, and means only effective responsive to afurther operation by the calling subscriber for causing said switch toseize said preselected trunk line and make thevsame busy.

18. In a telephone system a calling line, a repeater, a iirst, a second,and a third nonnuinerical switch individual to said repeater, a first, asecond, and a third group of trunl: lines, means responsive to theremoval of the calling subscribers receiver for seizing said repeater,and means responsible to the seizure of said repeater for causing saidiirst switch to seize an idle trunk line in said first group and forcausing said second and third switches to preselect but not seize andmake busy an idle trunk in said second and third groups, respectively.

19. In a telephone system, a calling line, a repeater, a first, asecond, and a third non numerical switch individual. to said repeater, afirst, a second, and a third group oi: trunk lines, means responsive tothe removal of the calling subscribers receiver for seizing saidrepeater, means responsive to the seizure of said repeater for causingsaid first switch to seize an idle trunk line in said first group andfor causing said second and third switches to preselect but not seizeand make busy an idle trunk in said second and third groups,respectively, and means responsive to a further act by the callingsubscriber tor causing either said second or third switch to seize thepreselected trunk line in its associated group;

20. ln a telephone system a calling liner, a repeater, first, a second,and a third non numerical switch individual to said repeater, a lirst, asecond, and a third group of trunk lines, means responsive to theremoval of the calling subscribers receiver for seizing said repeater',means responsive to the seizure ot said repeater tor .causing said firstswitch to seize an idle trunk line in said first group and for causingsaid second and third switches to preselect but not seize and make busyan idle trunk in said second and third groups, respectively, meansresponsive to a further act by the calling subscriber for causing eithersaid 'second or third switch to seize the preselected trunk line in itsassociated group, and means responsive to said last means for releasingsaid first switch to Jfree the seized trunk line in the lirst group.

2l. n a telephone system, a main exchange, a plurality of satelliteexchanges associated vWith said main exchange byl trunk lines, aregister controller in said main exchange common to said satelliteexchanges, means responsive to a. call for seizing and operating saidregister controller 'from any one of said exchanges, and means in saidregister controller for determining Whici one of the exchanges the calloriginated in.

22. ln a telephone system, a main exchange, a plurality of satelliteexchanges associated with said main exchange by trunk lines, a registersender in said main exchange, means responsive to a call from any one otsaid exchanges for seizing and setting said sender in the positioncorresponding to the called exchange, means in said sender fordetermining which one of said exchanges originated the call, anddiscriminating means in said sender for releasing said sender in casesaid sender is set in a position corresponding to the satellite exchangeoriginating the call.

23. In a telephone system, a main exchange, a satellite exchange, trunklines conneet-ing the main exchange With said satellite exchange, branchlines, three switches in said satellite exchange, means in saidsatellite exchange responsive to a call for causing the first o'l saidswitches to seize an idle one of said trunk lines, and means in saidmain exchange for thereafter selectively operating either the second orthe third of said s vitches over the seized trunk line to seize adesired one ot said branch lines.

2t. ln a telephone system, a main exchange, a plurality of satelliteexchanges, i ter senders only in said main exchange, i. sans responsiveto the initiation'of a call by a calling subscriber in any one of said iin serial relation over which talking connectionsto a calledline areestablished, means for seizing one of said senders by Way of saidcircuit, and means in said seized sender for transmitting a distinctivesignal back over said circuit cooperate apparatus in said repeater whenthe full number of digits of a called line have been dialled.

E26. ln a telephone system, register senders,

a talking circuit including arepeater, a;

switch, and a tvvo conductor trunk line in serial relation over Whichtalking connec`' tions to a called line are established, means torseizing one of said senders by Way of said circuit, and means in saidseized sender l for transmitting a distinctive signal back over only onetalkingconductor of said circuit to operate apparatus in said repeaterresponsive to the calling subscriber dia-lling the digits of apredetermined ottice code.

27. ln a telephone system, register senders, a talking circuit includinga repeater, a switch, and a tvvo conductor trunk line in serial relationover Which talking connections to a called line are established, meansfor seizing one of said senders by Way of vsaid circuit, means in said4seized sender for transmitting a distinctive signal back over only onetalking conductor of said circuit to operate apparatus in said repeaterresponsive to the calling subscriber dialling the Vdigits of apredetermined oiiice code, and

means in said sender for transmitting a distlnctive 'signal back 'overonly the other talking conductor oi' said circuit to operate apparatusin said repeater in case the calling subscriber dialled the digits of adierent predetermined otiice code.

28. In a telephone system, a iirst exchange,

a second exchange, a repeater in said first exchange, a plurality ottrunk lines extending from said repeater, the iirst of said trunk linescomprising only tivo talking conductors extending to said secondexchange,

means responsive to a call by a calling sube scriber in the firstexchange 'for seizing said repeater, means responsive to the seizure ofsaid repeater for extending the connection over said first trunk line tothe second exchange, means in said repeater controlled over only one ofsaid conductors responsive to a predetermined act of the callingsubscriber for disconnecting the calling subscriber from said firsttrunk line and for connectingsaid subscriber to another ot said trunklines, and means in said repeater controlled Vover only the other ofsaid conductors in case a different predetermined act is perL formed bythe calling subscriber for causing the disconnection of the callingsubscriber from said first trunk line and for Connecting the callingsubscriber to a third of said trunk lines.

29. In a telephone system, a chain of relays, a conductor normallyconnected to the first of said relays over a circuit including a pair otcontacts on each of said relays, means for closing a circuit over saidconductor to operate any number of said relays, the circuit forenergizing the second of said relays including said conductor andcontacts on all of said relays, the circuit for energizing the third oitsaid relays including said conductor and contacts on all of said relaysexcept the iirst relay, and the circuit for energizing the fourth relayincluding said conductor and contacts on allsaid relays except the firstand second relays, and means controlled by each of said relays forclosing a locking circuit for itself. I f

30. In combination, a plurality of relays, the irst relay `beingarranged to operate responsive to a relatively small current flow, eachsucceeding relay requiring a larger current tlovv than the oneimmediately preceding it, an operating conductor extending to the firstrelay, means for setting up a current lovv of desired predeterminedstrength over said operating conductor, contacts on the iirst relayoperated if the lirst relay responds to the current flow Jfor extendingthe operating circuit to the second relay,

and contacts on each relay after the iirst and except the last operatedif the relay responds to the current flow for extending the operatingconductor to the succeeding relay.

3l. In combination, a plurality of magnets, one of said magnets beingarranged to operate responsive to a relatively small current new, eachsucceeding magnet requiring i a larger current floiv for its operationthan is required by the magnet immediately preceding it, an operatingconductor, means for conditioning said conductor to transmit a currentflow of desired predetermined strength therecver, and means forconnecting said operating conductor to said magnets successively.

32. In combination, a plurality oi' magnets, one of said magnets beingarranged to operate responsive to a relatively small current iovv, eachsucceeding magnet requiring a larger current flow for its operation thanis required by the magnet immediately preceding it, an operatingconductor, means for conditioning said conductor to transmit a currentioW of a desired predeterminedV strength thereover, means for connectingsaid operating conductor to said magnets successively, and meansincluding a separate was@ circuit for maintaining any magnet in anoperated condition that responds to the current iioW over the saidoperating conductor.

38.7In combination, a plurality of magnets, one ot' said magnets beingarranged to operate responsive to a relatively small current flow, eachsucceeding magnet requiring a larger current flow for its operation thanis required by the magnet immediately preceding it, an operatingconductor, means for conditioning said conductor to transmit a currentilow of a desired predetermined strength thereover, and means forconnecting said operating conductor to said magnets successivelybeginning with the one which responds to the smallest current andcontinuing With the magnets in the order of their operatingcharacteristics.

In Witness whereof, I hereunto subscribe my name this 26th day ofJanuary, A. D.

FRANK TENCH.

